Stroke is associated with the blockage of blood flow to one or more sites of the brain. If the period of blockage is long enough, the stroke leads to cell death. Usually, the initial zone of cell death is relatively small and if the stroke were limited to that region, the effects might be relatively mild. However, the death of the cells leads to an inflow of fluid to the region, the degradation of the cells, and the release of intracellular contents. The effect is that the region of cell death becomes enlarged, so as to greatly increase the number of neurons involved in the loss of cell function.
It is believed that if one could rapidly increase the blood flow to the region, where the initial blockage occurred, the effects of the stroke could be substantially diminished. In many instances, mortality could be prevented. It is also of interest to be able to treat people who are susceptible to the formation of clots, particularly under conditions where the potential for clot formation is enhanced, such as operations.
It is not simply a matter of increasing the heart rate or blood flow to the heart since this may have only little or no effect on the amount of blood through the brain capillaries. Therefore, effects one may observe with blood vessels associated with other organs may not be translated to the effect one may anticipate in the case of stroke. Furthermore, there is substantial difficulty in being able to evaluate a drug as to its effectiveness in ameliorating the effects of stroke. Using individuals for various tests does not necessarily reflect the effectiveness of a drug, since a number of factors may come into play unrelated to the drug, but rather associated with holistic or placebo effects. There is thus a need for a carefully controlled test system for evaluating the efficacy of potential drugs for treating stroke.